Many hundreds of thousands if not millions of users utilize IMAP to receive email on their phone apps, thunderbird, outlook, etc. Support for it is expected of

Many hundreds of thousands if not millions of users utilize IMAP to receive email on their phone apps, thunderbird, outlook, etc. Support for it is expected of any mail provider as part of the basic requirements of operating an email service. Extending this with an extra means of authentication is comparatively easy to adding it to your web app.